Device for and method of setting spark plug electrodes



Sept. 13, 1949. L.. M. OBEN, sa 2,481,530 DEVICE FOR AND METHOD OF SETTING PLUG ELECTRODE Filed Aug. 3l, 1944 5 Sheets-Sheet 1 LEwrs IVI.v ODEMSR.

` m I v www DEVICE FOR AND METHOD OF SETTING Sept. 13, 1949. 1 M, opEN, 5R 2,481,530

SPARK PLUG ELECTRODES Filed Aug. 31, 1944 5 Sheets-Sheet 2 [gllllm MIIIIIII'W lllllllll I Ewls M. UDEN, 5R.

Sept. 13, 1949. L. M. ODEN, sR

A I DEVICE FOR AND METHOD OF SETTING SPARK -PLUG EIJEGTRODES 5 Sheets-Sheet 3 Filed Aug. si. 1944 l.. M. oDEN, 2,481,530

DEVICE FOR AND METHOD SETTING SPARK PLUG ELECTRODES Filed Aug. 31,' 1944 5 Sheets-Sheet 4 Sept. 13, 1949.

y l r w )l l g l 'x38 L @s 79 iwi/s ODM, 5H.

@ya s@ 054 www:

Sept 13, 1949. L. M. oDEN, sR 2,481,530-

' DEVICE FOR AND `M HOD -OF SETTING SPARK PLUG ECTRODES Filed Aug. 31, 1944 5 Sheets-Sheet 5 H mu Patented Sept. 13, 1949 OFFICE DEVICE FOR AND METHOD F SETTING SPARK PLUG ELECTRODES Lewis M. Oden, Sr., Ocean View, Va.

Application August 31, 1 944, Serial No. 552,113

22 Claims.

(Granted under the act of March .3, 1883, as

amended April 30, 1928; 370 O, G. 757) This invention relates to devices for and a method of adjusting the gap between the central and outer electrodes of spark plugs.

The Operation o adjusting the gap between the electrodes of a spark plug is ordinarily a time consuming and tedious operation when done by the commonly practiced methods. Frequently, the gap is made too small, and in the resulting attempt to separate the electrodes a bending mo.- ment is exerted on the central electrode which will fracture the porcelain, thus ruining the spark plus.

It is the major object of my invention to provide a machine which will accurately set the gap between the electrodes in a quick operation, in such a .manner that the central electrode will not be strained.

1t is another important object of my invention to provide a spark plug gapping machine wherein at least two outer electrodes can be ac curately and simultaneously positioned with respect to the central electrode.

Another object of the invention is to provide a spark plug gapping machine which is simple and fool proof in operation whereby an unskilled person can be taught to operate it with a minimum oi instruction and practice.

Other objects will be apparent as the descrip tion proceeds in connection with the drawings, in which:

Fig. 1 is a, side kview .oi one embodiment of the mahle;

Fig. 2 is a front View of the machine shown in Fig. .1;

Fig. :3 is a partial vertical sectional view along the line '3e-f3 of Fig. A2, looking in the direction of the arrows;

Fig. 4 is a sectional view along the line li-t of Fig. i, looking in the direction of the arrows;

Fig. 5 is an enlarged partial sectional view showing a gapping operation on a spark plug;

Fig. .6 is an enlarged partial sectional View showing a gapping operation on another type or" spark plug, using a modified gapping head;

Fig. '7 is a sectional View through the gapping head .of Fig. 5, along the line le-1 of Fig. 5 and looking in the direction of the arrows;

Fig. 8 is an enlarged pictorial View of one .of the ieelers used in the embodiment of Fig. 5;

Fig. 9 is an enlarged pictorial View of an ad". justor member as used in Figs. 1 to .5 and 7;

Fig. 10 is an enlarged pictorial View of the ad justor member used in the embodiment of Fig. 6;

1 Fig, ii an enlarged pictorial view of one of the feelers used the embodiment ci Fie. 6;

" piece Fig. 12 is .a pictorial View of a bent hold down plate used particularly with the gapping head shown in Fig. 6; .and

Fig. 13 is a View of a part of Fig. 3, showing a modicaton.

As shown in Figs. 1 and 3, the machine .coinprises a frame or arbor casting i0 which has op.- posing upper and lower jaw portions Il and l2, and a dat base I3 with bosses I4 and i5 which are bored to receive bolts I6 or the like for fas.- tening the machine to a support.

The upper jaw l! has two parallel bores I8 and I9 (Fig. 3) perpendicular to the jaws Il and l2. A rack 28 has a sliding fit in bore i8 and is moved up and down in the bore by means of a pinion 2| which is journalled in the jaw ll and engages the teeth on the rack. An operating handle 22 is fixed to the pinion shaft 23 to rotate it in operating the jrack.

The rack 20 has a central bore 25, the lower end of the bore accommodating with a sliding nt a stud 26 which projects upwardly from a gapping head 21. A coiled compression spring 2B is located within the bore 25, with its bottom end on top of the stud V26 and its upper end against an internal shoulder 29 where the diameter of the bore is reduced. A bolt Si! fits inthe reduced bore 3l :index-tends through the spring 28. The head .of the bolt vengages the top of the rack 2!` and its threaded lower end has engagement with the threads in a tapped hole in the stud 26. IThus the spring 28 is compressed between the shoulder 2 9 .and the top of the stud 26 and the head of the bolt 3D is held against the top of the rack 2.0. The axial position of the stud 25 in the bore 25 is adjusted by turning the bolt 35 by its head.

Adjacent its upper end the rack 2e is reduced in diameter to provide a shoulder 33. A crossor yoke 34 has a -bore therethrough which has .a press fit over the reduced portion of the rack and seats against the shoulder 33. A ta, pered pin 35 passes through both the yoke and the rack to X them in their relative positions. A bushing 36 having a central bore 31 is threaded through the yoke adjacent its other end.

Passing through the central bore 31 in the bushing is a push-rod 38, there being means such as set-screws 39 to x the axial position of the push-rod in the bore. At its upper end the pushrod has a handle or knob 42 threaded thereon, by which means the push-rod positioned in the bore 31 'when the set-screws 39 are loosened. At its lower end the push-rod is threaded into the upper part of a wedge 43, the wedge and the botof the upper jaw portion I I and within the bore The upper surface of the bushing 45 provides a seat for a compression spring 46 Which-surrounds the push-rod 38 and extends between the` jaw II and the underside of the yoke 34, there being a washer 41 between the top ofthe `spring and the yoke, having a recess to locate upper end of the spring properly about the push-rod.v Thespring 46 aids the lifting ofthe push-rod, yoke,

and rack back to their uppermost position after they have been lowered by the pinion 2| during a gapping operation and is strong enough to keep these parts in their uppermost position when no downward force is applied to the handle 22.

A support 58 which may be a casting having a substantially U-shaped or channel-like crosssection as shown in Fig. 3, is fastened to the upper side of the lower jaw I2 by bolts 5I or the like. The channel of the support extends transversely of the jaw, thus defining forward and rear legs 52 and 53. A pair of oppositely disposed jaws 54 and 55 (Figs. 2 and 4) are plvotally mounted on top of the forward leg 52 by means of screws or the like 56 and 51 respectively. A yoke 58 overlies the pivoted jaws, the screws 56 and 51 passing through the yoke with their heads on top of the yoke. At their rear ends the jaws overlie the rear leg 53 of the support 58 and are pivotally connected to a pair of cam followers 62 and 63 respectively by pivot screws 54 and 65. The cam followers slide on the top surface'of the rear leg 53 which is in substantially the same plane as the'topV surface of the front leg 52. At their inner and adjacent ends the cam followers 62 and 63 are provided with rollers 66 and 61 respectively which rotate about axes parallel to the top surface of the leg 53, the rollers being engaged by the opposite inclined faces of the wedge 43. A groove or track 68 is provided in the top surface of the rear leg 53, the rollers 66 and 61 being restrained from sideways movement by the walls of the groove, as shown in Fig. 3.

As shown in Fig. 4 a tensioned coil spring 69 is connected tothe jaws by eye-bolts 1|) and 1| to spread the opposed jaws vapart and to urge the cam,l followers 62 and 63 together, so that the rollers 66 and 61 are resilientlyA held against the inclined faces ofthe wedge. A guide plate 14 is ixedto the back of the rear leg 53 in any desired manner, the back face of the wedge 43 resting thereagainst and being guided thereby between the rollers 66 and 61. Set-screws 15 and 16 (Fig. V4) are adjustable in lugs attached to the rear leg 53 to engage the inner ends ofthe jaws 54 and 55 and limit their inward travel, there being lock nuts on the set-screws to tighten them in their adjusted positions. Y

From the above description it is seen that when the pinionl 2| is rotated to lower the rock 20 and push-rod 38, the wedge 43 is moved downward toward the rear leg 53 of the support 50, its opposed inclined faces engaging the rollers 66 and'61 and moving the jaws about their pivots 56 and 51 against the tension of the spring 69 so that their outer ends move towards each other. When the rack, push-rod, and wedge aremoved upward the outer ends of the jaws 54 and 55 separate due to the action of spring 89.

The lower jaw portion I2 of the frame I0 projects farther forward than the upper jaw 'to provide a projecting support 11. This support 11 has a recess 18 as best shown'in Figs. 2, 3 and 4. A plate 19- having a recess aligned with the recess 18 is fastened to the top of the projecting sup- -port 11 by screws 80 and 8|. The support 11 with the plate 19 form a base onto which an adaptor 84 can be slid'through the open 'end of the recess 18. As bestshown in Figs. 3 to 6 the adaptor has a loose fit .withinthe recess so that it can be shifted in the plane of the plate 19; there being a radial flange 85 which overlies the edges of the plate to support the adaptor. The front wall of the forward leg 52 is recessed at 86 to prevent interference with the radial flange 85.

The adaptor has a central bore with an inwardly extending radial flange 82 to support a spark plug as shown in Figs. 3, 5 and 6.V Itis Vintended that the spark plug nt loosely in the" adaptor and the adaptor t loosely in the recess 18.so that the spark plug can be easily shifted and aligned with the gapping head' 21 before? the gapping operation is begun.

In Fig. 5 is shown an enlarged viewv of the'gap-l' ping head during a gapping operation. A sparkV plug 81 is seated in the adaptor 84 which has been slid into the recess land isy resting onv the plate 19.v A second Vring adaptor 88 within adaptor 84 may be used torraise the spark plug 'to the properi body portion 89 having an oifset to the 4right as viewed in Fig. V3 and from which. the stud 25 extends. As shown in Figs 3, 4 and 7, the forwardVV face of the body portion has a vertical slot 90 ex?" tending from top to bottom. An adjuster member 9| (Figs. 3, 7 and'9) is section for the lower half of itslength, its central leg 92 sliding in the slot 99. The upper half of its length does not havethe Vcentral Vleg 92. At its top portion 93 the central leg has `a sliding t in the slot 90, the rest of theV central leg beingVv narrower, the narrow portion terminating at shoulders 94 and 95 (Fig. 9). The narrow portion of the central leg below and 95 is to provide space for oppositely disposed and similar feelers 96 and 91, the leg. The feeler 96 is shown pictorially in Fig.

8. As shown it has a wide flat portion 98 at ther top, and a narrower fiat lower portion 99 of substantial length which terminates in a bottom por-V tion |00 periphery of the central electrode IUI of the spark plug as shown in Fig. 5. The thickness of the two feelers 96 and 91 plus that of the central leg 92 of the adjuster 9| below the shoulders 94 and 95 are such that when assembled the adjuster and the feelers may slide in the slot 99. The tops of the wide flat portions 98 of the feelers bear against the shoulders 94 and 95 so that the upward movement of the feelers in the slot 99 is limited by their engagement with the adjustor in this manner. Thus the vertical position of the adjuster 9| determines the vertical position Vof thefeelers within slot 99.V

The width of the wide'flat portions 98 of the T-shaped' -in 'cross-r the shoulders 94' one on each side of which is so shaped as to matewith the` the adjuster 4-I is therefore slightly spaced from the said fiorvvardface. -A plate IUI covers the front ofthe body portion Bil-ot thelgapping head 211, being vclamped thereto byliour vscrews 'N32 `to IBB. The plate iol has a vertical groove |05 slightly deeper than the thickness of the crosspiece IUT of the adjuster member 5I sotha't'the adjuster member and the feelers are notclamped against movement by the plate I-lll. A set-'screw IUS is threaded through the plate lill .as shown inFigs.'3'and`7 and engages the frontof thecrosspiece. When 'the set-screw los lis tightened against the adjustor BI 'the feelers S6 'and 91 are clampedbetween the bottom oi the slot .9D fand the cross-piece of the adjustor member, as shown most clearly in Fig. '7.

Means are provided to shift the adjustor '9| vertically within the lslot y8l) when the Vsetnscievv IUS is loosened. Shifting the adjuster provides vertical adjustment of 'the feelers Q6 Vand 91. A disc il Ill (Figs. V3, 4 and 5l is rotatably seated 'in the forward liaceoi the body portion 89, the disc being wider than the Width rof the slot 8D. A stud IH projects .from the 'iront face ofthe disc I'IQ, but voiset from the axis of the disc. The stud projects through 'a horizontal .slot IIV'2 in .the cross-piece IIl'I .and has a screw driver slot by which the disc can be rotated. When the setscrew IBS `is loosened, Vrotation of the stud IH and disc .I lil causes a raising or lowering ci the adjuster member due to .the engagement of `the ol'sct stud in the slot M2. In the embodiment of Fig. 5, Ausing the member El of 9, when raising the adjustor member as described, the operator must be certain that the 'ieelers are pushed upv/ard against-the shoulders gli and 9s.

Integral With the body portion 88' of the gap ping head 2'! .are a pair of arms H5 and M6 -extending at right rangles thereto as :shown vin Figs. Z'to 5. Each arm has two coaxial `bores (Fig. 5) extending therethrough, the outer bores Ill and II 8 being larger in diameterthan'the inner bores II-9fand IZI), there being shouiders I2! and at 'their juncture. Similar rams IZ'an-:l 112'! are disposed for sliding movement in the bores, the rams having portions of large and small diameter'to fit the corresponding bores in the 'arms VI'Iii and IIS, and there being shoulders on the rrams where their diameter changes. Similar coiled compression springs i223 and I29 surround `the small portions Vof the rams and are compressed between `the aforesaid shoulders on Athe rams and the shoulders IZI .and $22, the action of the springs being to urge the rains outward and away from Yeach other. Rotation oi the rams inthe bores is prevented by screws |32 and L33 which are threaded through the Walls of the arms and slidingly engage longitudinal slots I-34 and L35 in the rams. The screws I32 alsolim-it the axial movement of the rams when they engage the ends of the slots.

At their inner ends the faces of the rams are inclined to ysubstantially the same angle as the outer electrodes of the spark plug which is being gapped, as shown in Fig. 5. As also shown in Fig. 5, the underside of the rams are recessed at ISS for a portion of their length to avoid interference with the movementof the ram by the threaded portion of the spark plug.

In ordinary 'use a large number of identical spark plugs are gapped kat one time. If a difierent lot of another type of plug is to be gapped, Vthe rams shown can be 'replaced by others having their :inner ends properly tapered, and the `recesses |36 properly located so vas to accommodate 6 the plugs Tol this lot. In y.a vsimilar .niannertlie adaptor Bt and adaptor ringsdmay be changed to accommodatethe plugs ':of'the rrewrlot.

The action of the 'gapping head 21 during 'a gapping operation is Aas follows: After vthe spark plug ai has been mountedin its adaptor is in position to be gapped, the `gapping head is lowered by rotating the handle 22 and the pinion 2l. The gapping head is lowered with the rack even though slidablymounted inthe bore of the rack, because of the compression of the spring '23. While the gapping head is being lowered the operator guides the bottom portions |00 'of the opposed feelers'll andll'l into the gapsbetween the central electrode and a pair oi opposite outer electrodes, as illustrated in Fig. Y5. The loperator may shift or rotate the spark plugand its adaptorin the plane of vthe plate 19 to obtain proper alignment of the spark pli-ig andthe feelers While lowering the Agapping heed. A pair oi'vertically adjustable studs its and l5@ which are threaded into the support Vl engage the bottom Vof the arms -i l5 and IIS, when 'the gapping head 21 has moved downward to the desired position rfor Vgapping, as shown in Fig. 5. movement of the vgapping head is thus prevented. As `rotation of the pinion is continuedthe rack 20, yoke 34, push-rod 3s `and the wedge 's3 oontinue their downward movement. However, since the gapping head2? `cannot 'move further due to engagement ofthe arms Ilo and Its with the studs l'klil and 450, the stud "25 will vslide inthe central bore as and further compress the spring z8 against the shoulder 33. With the continued downward movement of the rack A2l) the opposed inclined portions of the bottom of the rwedge engage the rollers te and 61 to separate the cam followersz and B3 and rotate the jaws 54 and 55 so that'their outer ends'move towards-each other as ypreviously described. During this period, be fore the rains I2@ and 21 the'outer elseitrodes ofthe spark plug, the operator shift the plug and its adaptorsvad etc. to lproperly align the plug with the eelers and rams.

As the outer ends of the jaws move towards each other they engage the outer ends of the rams Ifz and i2? and ioro'e them 'towards each other until 'they engage the outer electrodos of the spark'plug. With continued movement oi the rams the opposite electrodes Yare both forced toward the central electrode `until they are stopped by the feelers 9o and 9'! which rare clamped between the vcentral andeutet electro des. Fig. 5 shows the apparatus in this condition, the outer electrodes being forced 'against the feelers which separate them from the central electrode. Fig. 5 thus illustrates the completion of the gap ping operation on apair of opposite outer electrodes exeept'forthe'reniain operation or with drawing the Yarns and feero from enpfagement ivtih `the spari: plug. Since the material of 'the spark plug electrodes is somewhat resilient, the outer electrodes will spring baci; slightly when the rains-are'withdrawn. For'this reason the iee'lers 96 ande? are a little thinner 'than the gap 'which is desired between the central outer eleo-1 trodes, so that when the outer electrodes 'spring back to their 'nnal position the final gap between the central and outer velectrodes will be 'the correct desired gap.

When the handle 22 is moved upward it will re lease -the rams and lift the feeleis from 'the gap between the electrodes. However, since the lfeelers will be slightly'bent at theirbo'ttorn as shown in Fig. 5, the lifting of the feelers vwill normally `Further downward liftthe spark plug too since the feelers do not lift easily from the gaps. In order to keep the spark plug from being lifted in this manner, a stop plate |46 (Figs. 1, 3 and 4) isfastened to the top of leg 52 by screws |4|. As shown in Fig. 4, the stop plate |4| extends forward and overlies the rear of the threaded portion of the spark plug which is shown in dotted lines in Fig. el. The stop plate holds thespark plug down and thus the feelers are withdrawn from the gap when the handle 2'2 is raised. The plate |40 is just slightly above the spark plug so that it does not engage the plug when thev plug is inserted. under the gapping head or withdrawn after the gapping operation.

The withdrawal of the rams from the spark plug is automatic when the operator raises the handle 22, due to the action of the spring 69 which separates the jaws 54 and 55, and to the springs |28 and |29 which act to return the rams to their outer positions. The vertical range of movement of the gapping head is less than that of the rack because of the sliding action of the stud 25vas previously described, and in fact the limits of vertical movement of the head are such. that the outer ends of the rams |26 and |21 will always be engaged with a portion of the outer ends of the jaws 54 and 55, this engagement resulting from the action of the springs |26 and |29.

In practice the adjustments provided by bolt 3U in the stud 26; by the engagement of set-screws 39 with the push-rod 38; by disc I |l| and stud I; by the use of different adaptors 84 and ring adaptors 88; by the adjustment of studs |49 and |50; and by screws 15 and 16 allow the machine to be adjusted to operate on spark plugs of a -wide varietyV of sizes; the time spent in adjusting the machine when changing from a lot of plugs of one size to alot of another size being inconsequential as compared to the rapidity with which the remaining plugs of the lot can be properly and accurately gapped.

The gapping operation described above, and illustrated in Fig. 5, simultaneously gaps the two opposite outer electrodes on a spark plug having outer electrodes diametrically opposite to each other. If the plug has four equally spaced-.outer electrodes it much be rotated 90 degrees after the first two opposed electrodes are gapped, so Ythat the remaining'two electrodes are in position for gapping. If the plug has six equally spaced outer electrodes a third operation is necessary, and soforth.

Because of the construction of the apparatus whereby the spark plug can be shiftedinto exact proper alignment with the feelers and rams be-f fore pressure `is exerted by the rams, the force applied to the outer electrodes bythe rams doesnot impose any. bending strain upon the central electrode. Due to the pvoted connection 44 between the wedge 43 and the push-rod 38, each ram exerts-a force equal to and opposite to that of the opposed ram, and during the gapping operation the outer electrodes are bent towards each other until they are stopped when the feelers and the central electrode become clamped between the outer electrodes as shown in Fig.V 5. The ma-l terial of the feelers 96 and 91 is sufliciently ex` ible so that they can be pulled out from the gap without disturbing the gap setting. This iiexi` bility is necessary when the contour of theigap: flares as shown in Fig. 5 since as is clear from that; figure the outwardly flared bottom portions |06 of the feelers must be squeezed towards each other as they are pulled upward out of the gap.

The gapping head shown in Fig.'5 is'particularly adapted for operations -on spark plugs whereinthe end of the central electrode is substantially; cylindrical so that the thrust of the rams is most effective when ,perpendicular .to the axis of the electrode. The gapping vhead of Fig. 6, however,`

is designed particularly for spark plugs havinga conically tapered central Velectrode asin the type shown mounted in the adaptor 84 in .-Fig. 6; The arms |56 and |51 and the rams liirandlfi!)l therein are substantially perpendicular to the surface of-the conical central electrode instead of perpendicular to its -axis as in the embodiment of Fig'. 5. The faces of the outer ends of the-,rams are parallel to the faces of the jaws 54 and `55 and the action of the gapping head shown in Fig.=6

is exactly the same as that of Fig. 5` except for' the direction of the force exerted by the rams.

The adjustor member |60 used in the gapping head of Fig. 6 is slightly different from ythat used by the head of Fig. 5. Fig. 10 shows the adjuster member |66 used inFig. v6, which differs vfrom that shown in Fig. 9 by the provision of opposite grooves |6| and |62 just under thewide top poretion of the central leg |64 of the adjustor member.

One of the feelers I 65 and |66 used in the gap' ping head of Fig. 6 is shown in Fig. 11'. As ap-` pears in Fig. 11 the feeler |66 has a lip |61v at right angles to the plane of the main body'of the feeler and at the top of the wide fiat portion |68, the lip being of such size as to fit into the groove |6| of the adjuster member |60. The lip |61 and groove 6| have the purpose of causing the feeler to move with the adjuster member whenV the adjustor member is raised by the rotation of stud |59, and also the function of preventing the feeler from being. pulled out of the gapping head when the gapping head is being raised and the feelerv is being pulled out of the gap between the inner and outer electrodes after a gapping operation.y This feature is more necessary when gapping a spark plug of the type shown in Fig. 6 because it is more diicult to withdraw the feeler from the gap than from the spark plug of Fig. 5, but it is to be understood that this feature of the lip on the feeler engaging a slot in the adju'stor member'is also advantageous when using a gapping head of the type of Fig. 5 because the feelers are then raised and lowered with the adjustor member when the position of that element is being adjusted. The width of the wide flat portion |63 of the feeler is such as to allow the feel'er to be clamped in theigapping'head bythe adjustor member by tightening the set-screw |12 in the same manner as when screw |99 is tightened in Fig. 5.

The lower end |13 of the feeler liitrisY ared slightly outwardly as shown in Fig. 1l so that it will have a shape and inclination Vmore closely: approximating its nal inclination' during'. a 'gapg'V ping operation as shown in Fig. 6. Because ofV this flare, the lower end is advantageously inserted into the gap between the rinner and `outer electrodes byrmovingit sideways throu'gh the gapY between adjacent outer electrodes. Y While only one feeler |66 is shown in detail in Fig. 1l it is to be understood that the opposite feeler |65 is identical .thereto except for the reversal of the directions in which the lip and inclined lower end Fig.' 6,-since stop plate |40 would' be too far aboveA the spark plug to hold-it in the intended manner when removingthe feelers. Y

In the modification shown in lig. 13, the. stop plate |40 has a tapped hole adjacent its forward end, to accommodate a machine screw |8l having an enlarged head .|8|. The screw is vertically adjustable in the-stop plate, havingrmeans such-as a hole through its head through which a pin can be insertedtoturn it,v and underlies the body por tion 890i the gapping head as shown. The screw |80 may be used instead of the two studs |49 and |59 because it limits the downward movement; of the gapping head when adjustedA to the` proper height. It will be seen from Fig. 13 that the body portion 89 will be stopped during its downward movement by the screw |80.

When using thegapping head of Fig. 6 the stop plate |42 may be provided with a screw IS@ in the same manner as plate Idil is provided therewith in Fig. 13, and theaction. willbe the same as with the screw in plate |40. If desired, instead of using the stop plate |42 with the gapping head of Fig. 6, the straight stop plate |40 may housed. When this is done, the screw |80A is reversed in the plate so that its head |8| is below the plate. The head |8| is large enough in diameter so that it will project over the base ofr the spark plug and hold it down when the feelers are withdrawn, in the same manner that the stop plate |42 does when used. When so used, the threaded end of the screw projects upwards through the plate and stops the downward movement of the gapping head.

Thus when'using the screw |80 instead of the studs |49 and |50 it is possible to eliminate the studs |49 and |50 and the stop plate |62 of rlig. 12

It will be understood that the above description and accompanying drawings comprehend only the general andl preferred embodiment of the invention and'that various changes in details o1 construction, proportionvand arrangements 0I parts may be made within the scope of the apended claims and without sacrificing any of the advantages of the invention.

The invention described herein may be manul factured and used by or for the Government of the United States ofl America for governmental purposes without the payment of any royalties thereon or therefor.

What 'is claimed is:

l.. A device for adjusting the gap in spark plugs comprising at least two equiangularly spacedfeelers mounted on said device and adapted te be inserted between the central and outer electrodes of a spark plug; means operable to simultaneously press the outer electrodes towards the central electrode with said feelers clamped therebetween, the forces exerted by said means against the cen trai electrode forming a closed force diagram without the imposition of any bending moment upon the .central electrode; and actuating means on said ldevice operable to first insert said feelers into the gaps and then to actuate said means.

2. A device for adjusting the gap in spark plugs comprising at least two equiangularly spaced feelers mounted on said device and adapted to be inserte-:l between the central and outer electrodes a spark plug; .first means .operable to insert said feelers into the gaps between said electrodes; second means operable to simultaneously press the outer electrodes towards the central electrode until said fee'iers are clamped therebetween, the forces exerted-'by said second means against the central elect-rode forniing a Iclosed force diagram without the imposition ofl any bending momen-t 10 upon. the central electrode; saidflrst means be# ing operable to actuate said second means after the insertion of said feelers has been completed.

3. The apparatus'described in claim 2fwherein the i-orces exertedby said second means, and consequently the force diagram thereof, lie substantially in a plane perpendicular to the axis of the central electrode of the spark plug.

4. The apparatus described in claim 2 wherein the forces exerted by said second means do not lie in the same plane, and their resultant is opposed by a force along the axis of the spark plug central electrode.

5. A device for adjusting the gap in spark plugs comprising a support adapted to support a spark plug so that it is freely shiftable in a plane perpendieular to the axis of its central electrode; at least two feelers mounted on said device and adapted to be inserted between the central and outer electrodes of the spark plug; first means-operable to insert said feelers into the gaps between said electrodes; second' means operable to simule taneously press the outer electrodes towards the central electrode until said feelers are clamped therebetween. said second means being so con structed and arranged that the forces exerted by said second means against the central electrode form a closed force diagram Iwithout the imposi tion of any bending moment upon the central electrode; said first means being operable to actuate said second means after the insertion of said feelers has been completed, and said support permitting the shifting of the sparkplug during the operation of said second means.

6. The device described in claim 5 wherein said first means is operable to pull said ieelers from the gap betweenA the electrodes; and stop plate means operable to hold` the plug during the removal of said feelers.

7. A device for adjusting the gap in spark plugs comprising a f ranie having a pair of spaced o p- Y posedjaws; one of said-jaws having means defining a, support whereby a spark'plug can benadjustably held with its electrodes extending towards the opposite jaw; means slidablyA mounted inthe said opposite jaw' for movement-towards and away from the spark plug; feelers carriedvby said slidable means for insertion into the gap between the central and outer electrodes of lthe spark plug, said feelers being mounted for relative movement with respect to said slidable means; atleast two opposed movable jaws carried by said rst jaw and operable to exert equal and opposed forces against the outer electrodes of the spark plug whereby the outer electrodes may be pressed towards the central electr-iode; wedge means operable to exert equal forces on said incr/able jaws; a push rod supported by the aforesaid opposite i aw and operable te actuate said wedge; a yoke connecting said push rod to said slidable means for movement therewith; and means journal'led in the aforesaid opposite jaw for moving said sliding means.

8. A device for adjusting the gap in spark plugs comprising a frame having s. pair ci spaced op1 posed jaws; the first ef said jaws hav-ing a support whereby a spar-l; plug can be adjustably held with its eletrcdes extending towards the op= posite jaw; slidable means mounted in said opu pesite jaw for reciprocative mot-ien towards and away from the ,Spark plus; e grassi-ee serried by said slidable vmeans and axially movable Awith respect thereto; feelers carried 'by said gapping head for insertion into the gap between the centralV and outer electrodes of the spark plug; at

11 least two rams carried by saidv gapping head and movable with respect thereto, said rams being operable to move towards each other and to bend the outer electrodes of the'spark plug towards the feelers which are thereby clamped between the central and outer electrodes; movable jaws pivotally carried by said first jaw, there being one movable jaw for each of said rams and each movable jaw having one end portion thereof engaging one of said rams to move said rams toward the spark plug electrodes; wedge means operable to exert'equal forces on said movable jaws; a push rod supported by the said opposite jaw and operableto actuate said wedge; a yoke connecting said push rod to said sldable means for movement therewith; means journalled in said opposite jaw for moving said sliding means; and an operating handle for rotating said journalled means.

9. The device `described in claim s wherein spring means are provided between said opposite jaw and said sldable means to oppose the movement of said sldable means toward the spark plug; spring means provided between said slidable means and said gapping head to oppose the movement of said gapping head with respect to said sldable means; and spring means provided between said movable jaws and rams, whereby movement of said sldable means will cause Vsaid gapping head and said rams to move in succession toward said spark plug. Y

10. The device described in claim 8 wherein movement of the operating handle in one direction moves said feelers towards. and into the gap between the electrodes, and movement of the operating handle in the other direction moves said eelers away from the spark plug and pulls them out of the spark plug gaps, and a stop plate mounted on said frame to hold the spark plug while the feelers are being withdrawn from the gap.

11. The device Vdescribed in claim 8 wherein said feelers are of substantial length and of flexible material whereby they can be temporarily flexed to conform to the gap spaces during adjusting operation and withdrawal `from the gap spaces without disturbing the gap setting.

12. The device described in claim 8 wherein said gapping head is provided with means to hold said feelers in various positions whereby the positions of said feelers can be accommodated so as to fit spark plugs of various dimensions.

13. The device described in claim 8 wherein stop means mounted on the first of said jaws are provided to limit the movement of the gapping head towards the spark plug whereby the gapping head remains stationary after said feelers have been inserted into the gaps, and while said rams are moving to bend the outer spark plug electrodes towards the central electrode.

14. The device describedin claim 8 wherein at least one adaptor ring is provided to properly locate the spark plug on the said first jaw with respect to said feelers and said rams, said adaptor ring being of such dimensions as to allow free shifting of the spark plug in a plane at right angles to its central electrode. f

15. The device described in claim 8 wherein two rams are carried by said gapping head, said rams being coaxial and lying in a plane at -right angles to the axis of the `spark plug electrode as it is held on said support.

16. The device described in claim 8 wherein two rams are carried by said gapping head, thev axes of said rams lying in a plane containing the axis of the central electrode of the sparknplug,

plug central electrode atequal angles, saidangles being other than ninety degrees.

17. A device foradjusting the gap in spark plugs .comprising feelers mounted on said. de.- vice and adapted forinsertion between the center and outer electrodes of a spark plug; means mounted on said device operablev to-cause the insertion of said feelers within the gaps and to simultaneously pressthe outer electrodes towards the .center electrode with said feelers inserted therebetween. 1 j

18. A methodof adjusting the gap in spark plugs having a central insulatedelectrode and annularly spaced ground electrodes; inserting at least two equiangular.spaced-feelers between the central and ground electrodes, then simultaneously pressing the ground electrodes vtowards the center electrode with the feelers inserted therebetween, the forces `exerted againstthe center electrode forming a closed force diagram without the imposition of any bending moment upon the central electrode.

19. In a machine adapted for gapping spark plugs, an adapter applicable for locating a spark plug in the center of and in definite relation in height to operative parts of the machine, and a gapping mechanism facing the electrodes of a located spark plug and comprising a movable head and a movable guide member operatively connected to said head, means. adapted to move said head and said member in a direction toward and from the electrodes of the spark plug, spacer elements on said guide member, insertable bel tween the center and outer electrodes during said members movement toward the spark plug, and means adapted to .force-,the outer electrodes against said inserted spacer elements under a pressurer exerted bysaid head suflicient to p roduce Va permanent gap between the center and outer electrodes of a size substantially that of the thickness of said spacer elements. y

20. In a machine of the character described, an adapter applicable for locating a spark plug in f 'l the'center of and in definite relation in height to operative parts of the machine, and a gapping mechanism facing the electrodes of a located spark plug and comprising a movableV head and a movable guide member operatively connected to said head, means adapted to move said head and said member in a direction toward and from the electrodes of the spark plug, spacer elements on saidguide member` insertable between the center andouter electrodes during saidmembers movement towardL the spark plug, means adapted to limit the movement of said guide member in relationA tothe height of the sparkY plugs electrodes and further means capable to force the outer electrodes against said inserted spacer ele- 1- ments under a .pressure exerted by said head sufficient to produce a permanent gap between the inner and outer electrodes of a size substantially vthat of the thickness of said spacer elements. v

21. A device for adjusting the gaps in Vspark plugs comprising at least two equiangularly spaced. feelers mounted on said device and adapted to be inserted between the central and outer electrodes of a spark plug; means operable to simultaneously press the outer electrodes toward the central electrode with said feelers clamped therebetween, the; f orces exerted by'said Y means against the central electrode-forming a closed force diagram without the imposition of anrbeadinsmemem um #lacentral electrode;

13 and actuating means on said device operable to first insert said feelers into the gaps and then to actuate rst named means.

22. A device for adjusting the gaps in spark plugs comprising at least two equiangularly spaced feelers mounted on said device and adapted to be inserted in the gaps between the central and outer electrodes of a spark plug; rst means operable to insert said feelers into the gaps between said electrodes; second means operable to simultaneously press the outer electrodes toward the central electrode until said feelers are clamped therebetween, the forces exerted by said second means against the central electrode forming a closed force diagram without the imposition of any bending moment upon the central electrode; and actuating means on said device to rst operate said first means and after the insertion of said feelers in the gaps to operate said second means, said actuating means including a Wedge member for driving said second means.

LEWIS M. ODEN, Sn.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 198,547 Meyer Dec. 25, 1877 867,011 Bromley Sept. 24, 1907 2,155,542 Graham Apr. 25, 1939 2,193,886 Schultz Mar. 19, 1940 2,235,172 Schultz Mar. 18, 1941 2,309,632 De Rentiis Feb. 2, 1943 2,321,854 Rabezzana et al. June 15, 1943 2,388,953 Coombs Nov. 13, 1945 

